Thin film transistor/liquid crystal displays appear to be the emerging display technology of choice. Worldwide efforts exist to develop this technology into practical display products. Crosstalk is high on the list of problems to be solved. This is a problem of coupling information intended for a picture element on a column into other picture elements on that column and adjacent columns. The resulting undesirable effects are visible on the screen. The cause is the parasitic (geometrical) capacitance between the column or data line and the conductor pad which defines the pixel. Even though the transistor connecting the data line to the pad may be turned off, the parasitic capacitance causes a fraction of the data voltage to appear on the pad, that is, across the liquid crystal pixel.
There are a number of prior art patents which directly or indirectly address the problem of crosstalk, although most of these deal with different types of crosstalk associated with conventional matrix liquid crystal displays.
U.S. Pat. No. 4,655,550 to Crossland et al is directed to a ferro-electric liquid crystal display in which the individual pixels are addressed via an address matrix that includes one field effect transistor for each pixel and a plurality of row and column conductors whereby data is written into each pixel to change or to maintain its display condition. Crosstalk is reduced by applying voltage selectively to only those pixels which are to be accessed.
U.S. Pat. No. 3,995,942 to Kawakami et al is directed to a method of driving a matrix type liquid crystal display device. Crosstalk between liquid crystal cells is reduced through the use of a bias voltage pulse.
U.S. Pat. No. 3,765,011 to Sawyer et al is directed to a flat panel image display having an addressing scheme utilizing 2 terminal breakdown switches.
U.S. Pat. No. 3,532,813 to Lechner is directed to a liquid crystal display that overcomes first order crosstalk of a simple X-Y addressing scheme, but is not applicable to other forms of crosstalk.
U.S. Pat. No. 4,660,030 to Maezawa is directed to an improved liquid crystal video display device. An interlacing video display technique is utilized and scanning signals are provided to every other scanning electrode line in sequential order, shifting selected lines every frame. An additional selected voltage is provided during the time period which overlaps the selected scanning electrode lines to the adjacent non-selected electrodes both above and below the selected scanning electrode lines. A high resolution display is provided while reducing associated flicker by driving all scanning lines in the desired order.
U.S. Pat. No. 4,640,582 to Oguchi et al is directed to a system for driving a liquid crystal matrix display for use in a television wherein the signal applied to each pixel is inverted at a rate not greater than that necessary to scan a single pixel but greater than the rate necessary to cause crosstalk and in any event greater than the rate necessary to scan a line of pixels without inverting.
According to the present invention, the elimination of crosstalk between data lines and pixel cells in a TFT/LCD is accomplished by applying a data signal to a given data line for a time period less than the standard scan line period of the display, and applying a crosstalk compensation signal to the given data line for the remainder of the scan line period.